World Heritage Sites are amongst the most important types of designated heritage asset and are inscribed by the United Nations Educational, Scientific and Cultural Organisation (UNESCO). The UK Government is a signatory to the World Heritage Convention which was established in 1972 by UNESCO, resulting in a list of sites, places, monuments or buildings of "Outstanding Universal Value" to all humanity - today and in future generations. The World Heritage List includes a wide variety of exceptional cultural and natural sites, such as landscapes, cities, monuments, technological sites and modern buildings. There are nearly 1000 World Heritage Sites worldwide, including the Great Wall of China, the Pyramids, the Great Barrier Reef and Venice. There are 20 World Heritage Sites in England, including Stonehenge, Canterbury Cathedral, Saltaire, Hadrian’s Wall and the whole of the City of Bath.
Accordingly, great weight should be given to their conservation in the planning process. Substantial harm to a World Heritage Site’s significance (the heritage aspects of its Outstanding Universal Value) or total loss of the site should be wholly exceptional. The government’s policy on assessing impact on World Heritage Sites is set out in paragraph 26 of the Planning Practice Guidance.